As Wang Chang tidies his boat on the southern Chinese island of Hainan, it could not be more peaceful. The 31-year-old fisherman has just sold his catch and the deck is drying in the sun.

But Mr Wang is plying a dangerous trade. Like 130 other fishing boats in Tanmen, a port on Hainan’s east coast, his dilapidated wooden vessel specialises in fishing in the Spratly Islands.

The archipelago, a three-day voyage from Tanmen, has become one of the main flashpoints where China and its south-east Asian neighbours clash over rival territorial claims in the South China Sea.

Rich in oil and gas, the area is one of the world’s busiest shipping routes, through which oil and other resources from the Middle East and Africa are transported to Asia and exports are carried to Europe. But new quarrels over fishing and resource exploration have revived old tensions in the area.

Just as Mr Wang is taking a break after a two-month Spratly fishing expedition, Chinese and Philippine vessels remain locked in a stand-off at Scarborough Shoal, a reef west of Manila, which was triggered by what the Philippine government says was illegal poaching by fishermen from Tanmen.

Such incidents are risky for the fishermen. Two of Mr Wang’s crew were shot by hostile coastguards two years ago. The fishermen constantly remind China’s neighbours of Beijing’s claims to these waters, even as there are signs Beijing is adopting a more moderate stance on the South China Sea dispute.

“The Filipinos put us in jail and confiscate our ships, and the Malaysians shoot right away,” says Wang Qingjin, the owner of one of the larger ships in Tanmen which supplies the Spratly fishermen with fresh food and buys their catch at sea. “The Taiwanese military doesn’t even let us come close. The Vietnamese are slightly better, they just chase us away.”

China’s neighbours have been blaming Beijing over the rising tensions after it started regular patrols of the Spratlys in 2010.

Following a series of failed attempts to make the problem go away by repeating its mantra that it does not threaten anyone, Beijing is finally trying to respond. In February, a foreign ministry spokesman said: “No country including China has claimed sovereignty over the entire South China Sea”.

Experts welcomed the statement as a long-overdue clarification, as Beijing had always kept its claims deliberately vague. Chinese maps encircle the South China Sea with a line of nine dashes that runs up to large stretches of the Vietnamese, Malaysian and Philippine coasts.

The “nine-dotted line” first appeared on a map published in 1947 by the Republic of China and inherited by the People’s Republic of China.

After Beijing’s statement, some scholars say China may change tack and base its maritime claims on the UN Convention on the Law of the Sea (Unclos), which takes into account the land, such as islands and reefs, under a country’s sovereignty.

Wu Shicun, president of the National Institute for South China Sea Studies in Hainan, a think tank that advises the foreign ministry, says the international community “forced” China to move.

“The Chinese claim is not what the international community has thought it to be – that China claims all 2m sq km inside the ‘nine-dotted line’ as territorial waters,” he says.

Taylor Fravel, a US expert on Chinese security, argues that Beijing has opened the door to an eventual settlement of the dispute. “China could advance a large claim to maritime rights in the South China Sea from the islands and other features in the Spratly Islands,” he wrote last month.

Mr Fravel added that China basing its claims on Unclos would have the advantage that “disputed and undisputed areas would be clearly identified” and that it would also “allow states to invoke the dispute settlement mechanisms of Unclos”.

However, the road to that goal is challenging. While Chinese scholars increasingly say Beijing must make a case that is compatible with Unclos, many government officials and the military oppose abandoning the nine-dotted line since it is seen as a sign of historic rights in the South China Sea. “Now we mainly lean towards the explanation that [the line] means all islands inside it are Chinese territory, and that it demarcates an area inside which China has certain historic rights: fishing rights, navigation rights . . . resource exploration rights,” says Mr Wu.

Even the cautious step towards a more moderate stance in the South China Sea dispute is triggering a backlash at home.

“It is going to be very difficult to stick to this foreign policy line because the public has been educated to a nationalist view for decades,” says Zhang Mingliang, a South China Sea expert at Jinan University in Guangzhou.

The Tanmen fishermen care little about these arguments and just want to make a living. The government pays them a fuel subsidy, with those going out to the Spratlys getting an extra allowance.

Standing on the deck of his boat, Mr Wang says that “without that, we would be losing money”.